Combine beer, garlic, chipotles, onion, green chiles, lime juice, vinegar, cumin, oregano, salt, pepper and cloves in a blender or food processor. Purée for 30 seconds, or until completely smooth. Set aside.
Press the “Sauté” setting on the Instant Pot. Add oil. Then once it is heated and shimmering, add the roast and sear — turning every 45-60 seconds or so — until the roast is browned on all sides. Press “Cancel” to turn off the heat.
Add the bay leaves and pureed sauce, and briefly toss everything until the roast is evenly coated in the sauce. Close lid securely and set vent to “Sealing”.
Press “Manual”, then press “Pressure” until the light on “High Pressure” lights up, then adjust the +/- buttons until time reads 60 minutes. Cook. Then very carefully, turn the vent to “Venting” for quick release, and wait until all of the steam has released and the valve has dropped.
Remove the lid, and discard the bay leaves.
Using two forks, shred the beef into bite-sized pieces. Give the beef one more good toss in all of those juices so that it can soak them up.
Serve warm, or refrigerate in a sealed container for up to 3 days, or freeze for up to 3 months.